The family Calpytraeidae is made up of three
genera: Crepidula (slipper shells), Crucibulum (cup and saucer
shells) and Calyptraea (hat shells). All of the species have
limpet-shaped shells with an internal shelly septum. The genera are
distinguished by shell morphology. In Crepidula the shell apex is
directed posteriorly and the internal septum is a flat shelf that attaches along
both sides of the shell. In Crucibulum the shell is conical with a
central apex and a cup-shaped internal septum. In Calyptraea the shell
is conical with a central apex but the internal shelly septum is a coiled ramp.
Shells are often not diagnostic on the species level. Cryptic species often
co-occur but they can usually be distinguished on the basis of developmental
characters and body pigmentation. There are 6 species of Crepidula, one
Crucibulum and one
Calyptraea reported from Florida: Crepidula ustulatulina, C.
depressa, C. atrasolea, C. aculeata, C. maculosa and
C. fornicata, Crucibulum auriculum, and Calyptraea centralis.
The shell of Crepidula depressa
is generally flat and white, ranging from extremely recurved to somewhat convex
depending on the habitat of the individual. Those from exposed substrates are
often oval and convex. The septum is flat in convex shells and convex in
recurved shells, with a notch on the right side where it attaches to the shell.
There is also a depression in the center of the septal margin. Muscle scars are
absent. The shell is white inside and out, rarely with pinkish-brown streaks.
Length up to 4 cm. The translucent white body has opaque white on the tips on
the tentacles and the lips and some white spots in the mantle and neck lappets.
There is no black pigment on the foot and very little hint of yellow.
Potentially Misidentified Species
There are two easily confused congeners of Crepidula depressa living in the North Atlantic. Neither of these can be
distinguished from C. depressa on the basis of adult shell morphology. Crepidula atrasolea co-occurs with C. depressa along the coast of
Florida and can be distinguished from C. depressa by the black
pigmentation on the foot and direct development. Crepidula plana has a
white foot and planktonic larvae like C. depressa, but occurs from Nova
Scotia south to Georgia, although its range may extend into Florida. These two
species can be distinguished on the basis of details of the female reproductive
tract and DNA sequence data (Collin 2000).
Species with similar shells also occur in California, Chile, New Zealand, and the Mediterranean.
HABITAT AND DISTRIBUTION
Crepidula depressa occurs on the Gulf coast of Texas, the Yucatan Peninsula, and both the
Gulf and Atlantic coasts of Florida at least as far north as Lake Worth.
Crepidula depressa has been documented to occur in the southern portion
of the IRL. It is likely to have a more
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Shell length in Crepidula depressa is typically to 4 cm.
Crawls. Hatchlings are planktonic for 3 - 4 weeks prior to settlement.
All calyptraeids are protandric hermaphrodites: small, young animals are males that later change to females as they grow.
All species copulate. Females are able to store sperm for several months.
The females deposit eggs into transparent capsules that they brood between the
neck and the propodium. In some species, swimming larvae hatch from the
capsules; in others, benthic juveniles crawl away from the capsules. Crepidula
depressa embryos hatch into planktotrpohic larvae that persist for up to a
month before settling.
The small eggs produce typical planktotrophic veliger
larvae with a smooth, almost planspiral shell at hatching. There are usually at
least 100 eggs/capsule, but the number of eggs increases with female size.
Average shell length at hatching is 255mm. The larvae take 3-4 weeks to grow to metamorphosis.
Species in all three genera of the Calyptraeidae are suspension feeders. They collect phytoplankton on mucus covering the gills. Phytoplankton are then transported to the mouth on a mucus string along the dorsal right side of the neck. The string is drawn into the mouth by the radula.
Crepidula depressa are found in the low
intertidal to subtidal zones where they typically utilize the shells of other
mollusks for habitat. They are most common living on shells and
inside shells inhabited by hermit crabs. Maximum depth distribution is unknown.
No information is available at this time
Collin, R. 2002. Another last word on Crepidula convexa and a description of C. ustulatulina sp. nov. (Gastropoda:
Calyptraeidae) from the Gulf of Mexico. Bulletin of Marine Science 70: 177-184.
Collin, R. 2001. The effects of mode of development
on phylogoegraphy and population structure of North Atlantic Crepidula
(Gastropoda: Calyptraeidae). Molecular Ecology. 10: 2249-2262.
[This includes, C. atrasolea, C. depressa and C.
Collin, R. 2000. Phylogeny of the Crepidula
plana (Gastropoda: Calyptraeidea) cryptic species complex in North
America. Canadian Journal of Zoology. 78: 1500-1514. [This includes C.
depressa and C. atrasolea]
Report by: R. Collin, Smithsonian Tropical Research Institute
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Page last updated: Jan 2, 2005